The public health importance of understanding the factors that lead to tobacco use is indisputable. This longitudinal study is a unique opportunity to study prospectively the progression of tobacco use in the adolescent offspring of teenage mothers. In addition, because we have data on prenatal tobacco exposure (PTE), we are able to examine the long-term effects of PTE on the adolescent's growth, cognitive, neuropsychological, and behavioral development. The consequences of PTE are not well-understood, particularly as PTE may influence subsequent tobacco use. The Specific Aims are to: 1) Identify antecedent factors leading to the progression of tobacco use nitiation and escalation among adolescents who have been followed since gestation; 2) Continue the examination of the long-term effects of PTE on developmental outcomes, and compare these effects with the PTE effects on offspring of a similar low SES cohort of adult mothers; and 3) Explore the etiological role of PTE and its consequences on the development and progression of adolescent smoking behavior. The 400 women and their offspring have been followed since the fourth prenatal month and at delivery, 6 and 10 years. We have data on pre-and postnatal substance use, measures of the environment, and the mother's psychological, and sociodemographic status. We also have collected physical, cognitive, psychological, behavioral, and neuropsychological measures of the offspring at all phases. This proposal requests 5 years of funding to conduct assessments of the adolescents at ages 14 and 16. Continuing follow-up into adolescence will clarify the understanding of the development of high-risk behaviors across the ages when these behaviors emerge and escalate. Also, with further physical and CNS maturation in adolescence, we can assess whether effects of PTE on growth, cognitive, neuropsychological, and behavioral outcomes are maintained and whether new deficits occur with maturation.